While this pair of fully robotic legs aims to master humanoid movement, one central component within the machine could also allow it to help paraplegics learn how to walk again.

A team of researchers from the University of Arizona have successfully developed the world’s most physiologically correct pair of robotic legs. Mimicking human walking required reconstructing the complete human neural, skeletal and muscular systems. The researchers then simplified the sensory feedback systems and used these models to recreate human walking with a robot.

The robotic legs are regulated by an artificial central pattern generator (CPG). The CPG in human anatomy is a neurological system of connections found in the spinal cord (near the torso) that is responsible for producing and sending cadenced electric muscle signals throughout the body. These muscle signals are harmonized by the CPG as it responds to external stimuli. It’s because of the CPG that we are able to walk around rhythmically without actually thinking about walking.

A simplified form of a CPG is known as a half center and is comprised of two neurons alternating their production of an electric muscle signal. The researchers have created an artificial clone of a half center that generates electric signals and gathers feedback from sensors in the robotic legs. For example, its load sensor notices pressure changes when the angle of the surface being walked on has increased or decreased slightly. As a result, these robot legs can walk with the same effortlessness as a healthy adult human.

The research team’s goal was to uncover the unsolved mysteries behind how humans learn to walk as babies and to better understand the various steps that are involved in walking.

“Interestingly, we were able to produce a walking gait, without balance, which mimicked human walking with only a simple half-center controlling the hips and a set of reflex responses controlling the lower limb” said Dr Theresa Klein, co-author of the study. The current hypothesis is that, even before they learn to walk, babies already have a simple half-center, just like the one in the robot. As they gain more experience, the neural network learns how to support more complex walking behavior.

“This underlying network may also form the core of the CPG and may explain how people with spinal cord injuries can regain walking ability if properly stimulated in the months after the injury,” added Dr Klein.

Ultimately, these robotic legs will help scientists better understand spinal cord injuries and, perhaps most significantly, identify how to help paralyzed individuals walk again on their own. For that reason alone, this development could be pretty incredible.

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